Sub-pixel for a display with controllable viewing angle

ABSTRACT

A sub-pixel for an LED display, the sub-pixel comprising a first light emitting device having a first emission beam angle and a second light emitting device having a second beam angle, the second emission beam angle being different to the first emission beam angle. There is also described a display using a plurality of the sub-pixels.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/520,693, filed Apr. 20, 2017, which is a National Phase applicationof International Application No. PCT/EP2015/074545, filed Oct. 22, 2015,which claims the benefit of United Kingdom Application No. GB1418810.6,filed Oct. 22, 2014, which are incorporated herein by reference in theirentirety.

TECHNICAL FIELD

This invention relates to a display and to pixels and sub pixels for anoptical display device.

BACKGROUND

A category of display technology called the ILED (Inorganic LightEmitting Diode) display is an alternative to the better known LCD(Liquid Crystal Display) and the OLED (Organic Light Emitting Diode)displays. An ILED display does not have many of the negative qualitiesof LCD or OLED displays as its display sub pixels are based on ILEDlight sources and has all the advantages of this class of device. Thisresults in a display that has better performance characteristics than anOLED type direct view display as well as the robustness, long-life andstability that is inherent to ILED technology.

ILED devices may be controlled and driven via a number of methods. Anexample of a drive scheme includes the mounting of the devices on anactive matrix incorporating thin-film technology (TFT). TFT includesmetal oxide and amorphous silicon based transistors. This active matrixis also known as the backplane. ILED devices are currently driven and assuch are compatible with OLED type TFT drivers. Other methods includeusing passive matrix drivers or the packaging of the light sources withmonolithic drive circuits.

The current state of the art comprises of the arrangement of R, G and Bdisplay sub pixels to form a single display pixel. In a typicalconfiguration for an ILED display, R, G and B chips are packed togetherto provide the necessary light for each pixel of the display. In thisexample, each R, G and B chip has one emitting area per chip or, moregenerally, the whole active area of the chip illuminates to emit light.These are termed Single Element Chips (SECs).

Of central importance in the efficient performance of ILED devices isthe ability to extract the maximum amount of generated light for the LEDmaterial to the surrounds. In the majority of cases, this results in thelight leaving the device in a randomised manner. The light extracted inthis manner can be shown to have a Lambertian emission profile with ahalf width half maximum of 60°. It is also possible to extract lightefficiently with a narrower beam profile. An example of same can be seenin U.S. Pat. No. 7,518,149.

When ILED devices are used in an ILED type display, the viewing angle ofthe display is largely dictated by the emission profile of the ILEDdevice. The various layers within the display stack (such as a touchscreen, circular polariser, cover glass etc.) will have an effect butthis will not be as large as that of the initial emission angle.

In typical display products, a very narrow viewing angle is notdesirable and has many drawbacks. Examples include the inability ofmultiple viewers to view the screen simultaneously and the inability toquickly view the screen without having to move it to an optimumposition. A narrow viewing angle is beneficial in applications such asprivacy display.

For the above reasons, standard displays have wide viewing angles.Indeed, a display with a wide viewing angle is seen as an importantselling point. However, the amount of light required for a display overwide angles is significantly greater than of a display with a narrowviewing angle. Indeed, to a first order, the viewing angle is directlyrelated to the power consumption of the display. Since the display isthe primary source of power consumption, the requirements for anexcellent display have two contrasting requirements: a wide viewingangle and minimal power consumption.

The viewing angle of a display is one of the most important features. Awide viewing angle is required for most devices—especially if they areregularly viewed by more than one person. However, the need to producelight over a wide set of angles results in increased power consumption.

SUMMARY

An ILED display consists of an array of ILED elements. The viewing angleof the display is dependent to some degree on the emitting angle of theILED elements. A wide viewing angle requires more power than a narrowviewing angle for the same light output. However, a narrow viewing angleis less commercially attractive. By using ILED elements that have twodifferent emitting angles the viewing angle of the display can bechanged dynamically. This will provide for a display that has acommercially attractive viewing angle and can be driven in a very powerefficient mode.

According to a first aspect, there is provided a sub-pixel for an LEDdisplay, the sub-pixel comprising a first light emitting device having afirst emission beam angle and a second light emitting device having asecond beam angle, the second emission beam angle being different to thefirst emission beam angle.

The first and second light emitting devices may be configured forselective operation for adjusting a light emission profile of a display.A light emission profile of a display may comprise a viewing angle ofthe display.

As an option, the first and second light emitting devices are selectedfrom any of an LED, an inorganic LED, and an organic LED.

As an option, the first light emitting device is a first Single ElementChip and the second light emitting device is a second Single ElementChip. Alternatively, the first light emitting device is a firstAddressable Array Element on an Addressable Array Chip and the secondlight emitting device is a second Addressable Array Element on theAddressable Array Chip.

As an option, the first and second emission beam angles are determinedby any of:

-   -   a coating;    -   a lens;    -   surface texturing;    -   a mesa shape; and    -   contacts.

As an option, an emission beam profile of any of the first and secondlight emitting devices is non-isotropic.

According to a second aspect, there is provided a display comprising aplurality of sub-pixels as described above in the first aspect.

The display optionally comprises a modifying layer overlaid on thedisplay, the modifying layer arranged to modify light from the pluralityof sub-pixels.

The display optionally comprises a control device arranged toselectively control illumination of sub-pixels of the plurality ofsub-pixels. The control system is optionally selected from any of apassive matrix and an active matrix. The control system optionallyfurther comprises a user input device configured to receive an inputfrom a user relating to a desired light emission profile from thedisplay. As a further option, the control system further comprises asensor configured to receive an input, and the control system isconfigured to adjust a desired light emission profile from the displayin response to the sensor input. As a further option, the control systemis configured to adjust a desired light emission profile from thedisplay dependent on a number of users of the display. As a furtheroption, the control system is configured to adjust a desired lightemission profile from the display dependent on a type of content of thedisplay. As a further option, the control system is configured to adjusta desired light emission profile from the display dependent on any of alocation and an orientation of the display. As a further option, thecontrol system is configured to adjust a desired light emission profilefrom the display dependent on ambient light conditions.

According to a third aspect there is provided a method of controlling anoptical display device, the optical display device comprising aplurality of sub-pixels, each sub-pixel of the plurality of sub-pixelscomprising a first light emitting device having a first emission beamangle and a second light emitting device having a second beam angle, thesecond emission beam angle being different to the first emission beamangle, the method comprising selectively controlling a power to thefirst light emitting device and the second light emitting device.

According to a fourth aspect there is provided a computer devicecomprising:

-   -   an output connecting the computer device to the display and        configured to control a desired light emission profile from the        display; and    -   a processor configured to determine the desired light emission        profile from the display, the light emission profile relating to        an emission beam angle of sub-pixels of the display.

As an option, the processor is arranged to selectively illuminate afirst light emitting device of a sub-pixel, the first light emittingdevice having a first emission beam angle, and a second light emittingdevice of the sub-pixel, the second light emitting device having asecond beam angle, the second emission beam angle being different to thefirst emission beam angle.

According to a fifth aspect there is provided a computer programcomprising computer readable code which, when run on a computer device,causes the computer device to determine a desired light emission profilefrom the display, the light emission profile relating to an emissionbeam angle of sub-pixels of the display.

According to a sixth aspect there is provided a computer program productcomprising a computer readable medium and a computer program accordingto claim 20, wherein the computer program is stored on the computerreadable medium.

As an option, the computer readable medium is a non-transitory computerreadable medium.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates schematically a display comprising a plurality ofpixels;

FIG. 2 illustrates schematically various components of a display;

FIG. 3 illustrates schematically a relationship between various ILEDchip types;

FIG. 4 illustrates schematically an exemplary ILED layout;

FIG. 5 is a graph showing the illumination area and the ratio ofillumination area for various illumination angles;

FIG. 6 illustrates an exemplary micro-LED;

FIG. 7 illustrates schematically sharing of Addressable Array Elementsacross multiple display pixels using Addressable Array Chips;

FIG. 8 illustrates schematically a cross-section view of an exemplarysub-pixel comprising two light emitting devices; and

FIG. 9 illustrates schematically in a block diagram an exemplarycomputer device.

FIG. 10 illustrates schematically a display pixel with SECs of twoemission angles used.

DETAILED DESCRIPTION

The following abbreviations and definitions are used in the followingdescription:

-   -   Light Emitting Diode (LED) A semiconductor device which produces        light when the appropriate electrical bias is provided. It is        noted that a micro-LED (μLED) may be considered a type of LED.    -   Emitter Any light emitting source, generally an LED. It is noted        that a μLED emitter may be an emitter and may comprise only a        part of a μLED device.    -   LED chip A piece of semiconductor material that can generate        light and has been singulated from a semiconductor wafer on        which it has been fabricated.    -   Single Emitter Chip (SEC) An LED chip with only 1 emitting        region (or emitter). Generally the whole chip will illuminate,        although this may not be the case in respect of μLEDs.    -   Addressable Array Chip An LED chip which has more than one        distinct light (AAC) generating region (or emitter) that can be        independently addressed.    -   Addressable Array Element An independently addressable emitting        area (or emitter) (AAE) in an Addressable Array Chip.    -   Non-addressable Array An LED chip which has more than one        distinct light Element (NAC) generating region (or emitter)        which cannot be independently addressed.    -   Display Pixel: A component of a display that is used to build        the total image. It generally consists of R, G and B sub-pixels        which can be independently controlled to produce a range of        colours.    -   Display Sub-Pixel: A sub-section of the Display Pixel which        typically comprises a single colour (generally R, G or B).

Referring to FIG. 1, there is shown a display 100 comprising a pluralityof pixels 102 with individual Single Emitter Chips in each displaysub-pixel 104. Each sub pixel 104 may have two light emitting devices(not shown in FIG. 1) to provide redundancy in the event of one of thelight emitting devices failing.

FIG. 2 illustrates schematically the various components of a display. Adisplay image 200 is made up of display pixels 202, and a display pixel202 is made up of display sub-pixels (typically RBG) 204.

FIG. 3 illustrates schematically a relationship between various ILEDchip types. From FIG. 3, it can be seen that an LED chip 300 may have atleast three different types: an addressable array chip 302, whichcomprises a plurality of addressable array elements (or emitters) 304; anon-addressable array chip 306, which comprises a plurality of arrayelements (or emitters) 308 that cannot be addressed individually; and aSEC 310.

There is described a display design based on the design and assembly ofILED chips such that viewing angle of the display can be dynamicallychanged and will allow for significant reducing in display powerconsumption when a wide viewing angle is not required.

A display typically comprises a large array of individual displaycomponents that can be selectively illuminated—see FIG. 1. Thesecomponents are referred to as Display Pixels. In a multi-colour displaythe smaller components related to the different colours are calleddisplay sub-pixels. In general these different colours are red, greenand blue (R, G, and B).

For an LCD display, the display sub-pixels are created by colour filtersand a liquid crystal optical element to selectively allow thetransmission of light from a white LCD backlight based on the pixelstate. In an ILED display, individually addressable R, G and B ILEDs areselectively illuminated based on the pixel state. No colour filter orliquid crystal is required. As the size or resolution of a display isincreased the total number of LED chips required increases. The pixelswhich are illuminated are selected by the backplane.

As shown in FIG. 4, an ILED display pixel 400 comprises individualemitting ILED devices in R 402, G 404 and B 406 (referred toindividually as the display sub-pixels). These are Addressable ArrayChips (AACs). In an exemplary ILED display, the light extracted fromthese ILED devices is random and may result in significant losses intrapped light and also a display with a wide viewing angle. Some of thelight extracted from the LEDs may be trapped within the display due tospeculative reflections at interfaces or other optical effects. Theseresult in a reduction in display efficiency and may also contribute topixel crosstalk or pixel blur.

A more collimated emission beam from the ILED source will reduce themagnitude of the reflections and other artefacts. However, as notedabove, such a narrow viewing angle in a display is less desirable incertain applications from a consumer point of view.

In exemplary displays, two ILED emitters are placed at each displaysub-pixel 402, 404, 406—one with a wide beam profile and the other witha narrow beam profile. The relative drive current of each of thesedevices will largely dictate the viewing angle of the display. This willalso dictate the power consumption. Specifically, referring to the greensub pixel 404, the sub pixel 404 comprises two emitters 408 a, 408 b.The two emitters 408 a, 408 b may be located on a single LED device ormay be each located on different LED devices. The two emitters 408 a,408 b are individually addressable such that one of the emitters may beturned on while the other is turned off. Similar arrangements may bepresent in each of the red 402 and blue 406 sub pixels. Further, aplurality (and in certain exemplary display all) of the remaining pixelsin the display may have the same or a similar arrangement of sub pixels.

A number of exemplary method and apparatus comprise two ILED Elementsplaced together for each display sub-pixel to achieve performancebenefits—namely the ability to provide lower power consumption or wideviewing angle based on user requirements and to provide a privacyfunction to a display. In one embodiment, two individual ILED chips percolour each with different beam angles are used for each displaysub-pixel. For such a design, 4 contacts are required; one p and one nfor each ILED chip in a sub pixel.

Shown in FIG. 4 is an overview of the ILED display pixel 400. Eachdisplay sub-pixel 402, 404, 406 contains at least one individual ILEDemitter. The total number of display pixels 400 and hence displaysub-pixels 402, 404, 406 is dictated by the size and resolution of thedisplay. An example of an increasingly common display format for mobilephone devices is 1920×1080. In such a format the total number of displaypixels 400 is 2,073,600. The total number of display sub-pixels 402,404, 406 is 6,220,800. For a standard ILED type there would, therefore,be 6,220,800 individual Single Element Chips, assuming one chip for eachsub pixel.

As noted above, a number of techniques are used to maximise the lightextraction efficiency for ILED devices. These techniques generallyresult in light that is randomised from its light exiting surface. Thelight so produced may exit the ILED device equally in all directionsalthough more commonly it is shared across five surfaces (a frontsurface and four side surfaces) with the back surface (which is mountedto the carrier) being highly reflective. The overall beam profile fromsuch a device is dependent on the power escaping from the sides of thedevice relative to that from the front face.

In general the light from the front face will have a Lambertian profilee.g. a full width half maximum of 60°. Such devices when used in an ILEDtype display will result, to a first order, in a viewing angle of 60°.The power that is produced from the sides of the ILED chips may resultin losses or pixel cross talk, as it is not emitted directly out of theILED chip and, therefore, not directly emitted from the display. Anexemplary method to overcome such issues includes the use of reflectivebanks in a carrier substrate on which ILED chips are located, such aspatent application US20140159064. This is analogous to the use ofsecondary packaging in standard LED devices. These reflective banks areintegrated as part of the TFT panel manufacturing process. There is somescope to vary the beam angle/viewing angle of the sub-pixels based onthe design of the reflective banks. However, in reality, the ability tocontrol the beam angle using reflective banks is limited bymanufacturing techniques associated with TFT panel processing.

In exemplary methods and apparatus disclosed herein, the beam angle ofan ILED emitter may be measured on a wafer on which it has beenfabricated. This allows the relative viewing angles of displaysmanufactured using the ILED devices to be predictable, which is notachievable using current methods.

In exemplary displays, ILED devices are assembled in a display formatsuch that the viewing angle of the display can be changed based on userrequirements. This may be achieved by assembling a plurality of ILEDdevices within a sub pixel that have different emission beam profiles. Anumber of methods to produce such an assembly are outlined. In exemplarydisplays. ILED chips are used that are capable of producing light with awell-defined, narrow and/or controllable beam angle without the need forsecondary optical components. Such a device is outlined in U.S. Pat. No.7,518,149.

In one exemplary display, two ILED Single Element Chips are used foreach display sub pixel. Both of these ILED SECs will have well-definedemission beam angle profiles that differ from each other. For example,with reference to FIG. 10, one ILED SEC (Type A) may have a beam angleof 60° (Half width half maximum). The other (Type B) may have a beamangle of 20°. In the exemplary display 900 of FIG. 10, each pixel 1002comprises a plurality of LED emitters 1004 a, b in each sub pixel 1006.A first LED emitter 1004 a is a type A emitter and a second LED emitter1004 b is a type B emitter. The first LED emitter 1004 a has a differentemission angle to the second LED emitter 1004 b. The two emitters 1004a, b are individually addressable such that one of the emitters 1004 a,b can be illuminated when the other is not. In this way, the display1000 may be configured to use either the first or the second LED emitter1004 a, b. If the same arrangement is used for a plurality of pixels(e.g., all pixels) 1000 in the display then the viewing angle of thedisplay may be changed by switching between the sub pixel emitters 1004a, b. It is noted that whilst FIG. 10 shows two types of emitter havingdifferent beam angles, more types of emitter may be used.

When the display uses ILED SECs of Type A then, to a firstapproximation, the viewing angle will be 60°. When ILED SEC of Type B isused the viewing angle will be 20°. With Type B devices the powerconsumption for the display for a target forward luminance will besignificantly reduced relative to that of Type A devices.

Shown in FIG. 5 is the comparative light power required for variousviewing angles. A device with 60° angle of emission (Half Width HalfMaximum) requires more than 8× more light than a device with 20°half-angle emission to provide the same level of uniform illuminationover its target area. This translates to 8× more power consumption, orconversely a display using a 20° half-angle emission will consume 8×less power. In addition, a reduced viewing angle restricts viewing ofinformation displayed on the display by third parties outside theviewing angle, thereby providing increased security. Further, using thelower viewing angle setting allows increased brightness for the samepower as a lower brightness using the wider viewing angle. This can beadvantageous in bright ambient light conditions, such as in sunlight.

In another embodiment, only a single chip is used per colour/displaysub-pixel. However, this chip will be an Addressable Array Chip and willcontain two or more different Addressable Array Elements—emittingregions (or emitters) of which can be independently switched on or off.Each of these Addressable Array Elements will produce light from theILED chip with different beam profiles. In such a display, three or morecontacts are required—one for each p contact and one shared n contact.

A number of methods may be used to produce light from an AddressableArray Chip with two different beam profiles. It is generally recognised,as noted above, that producing light from an ILED device with goodextraction efficiency and a controlled beam angle is more challengingthan good extraction efficiency and a wide or random beam angle.Therefore, the use of devices such as that described in U.S. Pat. No.7,518,149 may be used to provide a particular beam angle of emission.These devices are termed μLED devices herein and generally comprise amesa structure and may be a type of ILED. References to ILEDs in thisdocument may also be references to μLEDs.

FIG. 6 shows an exemplary μLED 600. The μLED 600 shown in FIG. 6 is thesame or similar to that proposed in WO2004/097947 (also published asU.S. Pat. No. 7,518,149) having a high extraction efficiency andoutputting quasi-collimated light because of the parabolic shape. Asubstrate 602 has a semiconductor epitaxial layer 604 located on it. Theepitaxial layer 604 is shaped into a mesa 606. An active (or lightemitting) layer 608 is enclosed in the mesa structure 606. The mesa 606has a truncated top, on a side opposed to a light transmitting oremitting face 610 of the μLED 600. The mesa 606 also has anear-parabolic shape to form a reflective enclosure for light generatedwithin the μLED 600. The arrows 612 show how light emitted from theactive layer 608 is reflected off the internal walls of the mesa 606toward the light exiting surface 610 at an angle sufficient for it toescape the μLED device 600 (i.e. within an angle of total internalreflection).

There are a number of methods of increasing the beam angle of collimated(or partly collimated) light source—both on the chip and subsequently.In one embodiment, the surface of the ILED exit face may be roughened.This results in scattering of the light to wider angles as it leaves thechips. For a monolithic array it may be important that such rougheningis confined to the area that is illuminated by the emitter for which thebeam angle is to be modified. Therefore selective roughening of the ILEDchip's light emitting surface may be required.

In another embodiment, selective etching/shaping of the light exitingsurface may be used. This selective etching can be used to provide aparticular shape (e.g. convex and concave) to the light emitting surfaceof an ILED in order to narrow the beam profile of one emitter and, usinga different shaping, increase the beam angle (and possibly extractionefficiency) of another. It is noted that the ability to control thelight within the ILED chips, and hence selectively illuminate thefeature which may vary the beam profile, is a consideration in thesuccessful functioning of the Addressable Array Chips.

In another embodiment, structuring of the emission surface may be used.

In another embodiment, the ILED device includes an optical component,such as a polymeric lens, which changes the beam profile as the lightexits the chip.

In another embodiment, materials may be deposited on the light exitingsurface such that they vary the emitted beam angle. These materialsinclude, but are not limited to, filters, anti-reflection coatings oroxide based materials.

In another embodiment, the ILED emitter may be designed such that theemission profile from the device is not isotropic.

In another embodiment, the surface may be modified using any techniquesuch that the emitted light is no longer isotropic.

In another embodiment, more than two Elements may be used in eachAddressable Array Chip for each display sub-pixel. Each of these mayprovide a different beam profile. This would allow for additionalcontrol of the viewing angle of the display.

In another embodiment, the display sub-pixel may be formed usingElements (or emitters) which are on different Addressable Array Chips.Each of these Addressable Array Chips may contain Elements (or emitters)with one, or more than one, emission beam profiles. The emitters on eachmonolithic array can be shared by more than one display sub-pixel. Ascheme for doing this is shown in FIG. 7.

In another embodiment, all emitters on the Addressable Array Chipproduce narrow emission profiles. A secondary layer that is not part ofthe Addressable Array Chip may then be used to increase the beam angleof a selected number of these beam profiles. The overall viewing angleof the display can then be controlled by selecting Elements (oremitters) which are modified or not affected by the secondary layer.

In another embodiment, different parts of the screen may have differentviewing angles. This may be decided based on the contents or selected bythe user. For example, areas of the display that the user would like tokeep private may have a narrow viewing angle.

In another embodiment, the relative power of the emitters with differentbeam angles is controlled and modified such that the viewing angle isconstantly variable across a wide number of viewing angles. That is, itis possible to, for example, drive A (angle 20) at 10% and B (angle 60)at 90% to get a viewing angle of 50 degrees. It is also possible todrive, for example, A at 50% and B at 50% to obtain a viewing angle of40 degrees. Other ratios of drive current will be apparent to theskilled person.

In another embodiment, the light from the Addressable Array Chips iscoupled into an optical film such that this film will position the lightappropriately within the display pixel and may or may not change thebeam angle of the device.

The selection of the display viewing angle may be made by the user orautomatically by the operating system of the device in which the displayis used. The former can be referred to as Manual Viewing Angle Control(m-vac) while the later can be termed Automatic Viewing Angle Control(a-vac). There are a number of instances where the control system couldautomatically choose the viewing angle for the optimum balance of powerconsumption or viewing angle. This could be decided based on the type ofinformation to be displayed, the location of the device or using sensorsto assess the number of people interacting with the system.

In one instance of a-vac, the system sensor such as the camera canmeasure the number of users viewing or in a position to view the displayand adjust the viewing angle accordingly.

In another instance of a-vac, the viewing angle is reduced if the typeof message or sender is marked as private such that it is not easilyviewable by a person who is not directly in front of the display.

In another instance of a-vac, the viewing angle is increased for contentthat may be viewed by multiple people so as a film or video but reducedfor other types of media that is not consumed by multiple people as oncesuch as a business document.

In another instance of a-vac, the viewing angle may be dictated by theposition or location of the display. For example, if it is left flat ona table the display may automatically use a wide viewing angle as it islikely that the user will not be directly viewing it.

In another instance of a-vac, the viewing angle may be decided by theorientation of the display i.e. landscape or portrait.

In another instance, a-vac may be over-ridden by m-vac such that theuser can select the preferred viewing angle for all content.

In another instance, a portion of the display may have a wide viewingangle while another portion may have a narrow viewing angle.

A factor in the viability of a display is the total cost. For thecurrent invention, two emitters are used for each display sub-pixel.Such a design has the potential to increase the cost of the display.However, it should be noted that a second emitter may be required ateach display sub-pixel in any event as a redundancy measure to accountfor device failure. Therefore, the second pixel—which in the currentinvention has a different beam angle from the first—is required in thedesign. In certain embodiments above, the design is such that thematerial requirements and number of interconnections is not twice thatof a single pixel device.

ILED devices may be controlled and driven via a number of methods. Anexample of a drive scheme includes the mounting of the devices on anactive matrix incorporating thin-film technology (TFT). TFT includesmetal oxide and amorphous silicon based transistors. This active matrixis also known as a backplane. ILED devices are current driven and assuch are compatible with OLED type TFT drivers. Other methods includeusing passive matrix drivers or the packaging of the light sources withmonolithic drive circuits.

A method for the user to toggle between privacy mode (narrow viewingangle) to standard mode (wide viewing angle) will be provided by theoperating system.

Turning to FIG. 8, there is illustrated schematically a sub-pixel 800that comprises a first light emitting device 802 and a second lightemitting device 804. The beam angle of the first light emitting device802 is wider than the beam angle of the second light emitting device804, meaning that the first light emitting device 802 consumes morepower but allows a display to be viewed from a wider viewing angle. Thenarrow beam angle of the second light emitting device 804 reduces powerconsumption and also allows a user to view a display in ‘privacy’ mode.An operating system or computer programme may control the amount ofpower to each light emitting device, thereby controlling the viewingangle and power consumption of the display. As described above, thelight emitting devices may be on separate chips or the same chip. Notethat each sub-pixel may be provided with more than two light emittingdevices with different beam angles, allowing a greater degree of controlover the viewing angle of a display.

FIG. 9 illustrates schematically in a block diagram of an exemplarycomputer device 900. The computer device is connected to a display 902that comprises sub-pixels as shown in FIG. 8. A processor 904 controlsthe display and selectively provides power to the sub-pixels of thedisplay to affect the beam angle and hence the viewing angle of thedisplay 902. An input 906 is provided (for example, a user input or anambient light sensor) that provides data from which the processor 904determines the required viewing angle of the display 902. Anon-transitory computer readable medium in the form of a memory 908 isprovided, which is used for storing a program 910 which, when executedby the processor 904, causes the processor 904 to behave as describedabove. Note that the program may be provided from an external computerreadable medium 912, such as a CD, a flash drive, a carrier wave and soon.

Whilst specific embodiments of the invention are described above, itwill be appreciated that a number of modifications and alterations maybe made thereto without departing from the scope of the invention asdefined in the appended claims.

Numbered Clauses

1. An ILED type display in which the radial distribution of lightemitted from the display may be varied and as such the viewing angle ofthe display can be changed.

2. An ILED type display from which the radial distribution of light maybe varied and consisting of the following:

a. A plurality of ILED chips

b. A portion of the plurality of ILED chips are designed to haveemission beam profiles that are substantially different from the others.

c. A method of selectively addressing the ILED chips.

3. As clause 2, where the ILED chips are individual devices that have asingle emitting region.

4. As clause 2, where the ILED chips are Addressable Array Chips and theElements in the array are designed to have different beam angles.

5. As clause 2, where the ILED chips are Addressable Array Chipscontaining 2 or more Elements and all Elements are illuminating the samedisplay sub-pixel.

6. As clause 2, where the ILED chips are Addressable Array Chips and theElements on the same Addressable Array Chips may illuminate differentdisplay sub-pixels.

7. As clause 2, where the ILED chips have a coating, lens or other typeof component integrated to vary the beam angle.

8. As clause 2, where the ILED chips are Addressable Array Chips and acoating, lens or other optical components is used to selectively modifythe beam angle of selected Elements.

9. As clause 2, where the light exiting surface of the chips aretextured such that the beam profile of the light is selectivelymodified.

10. As clause 2, where the emission profile from the ILED devices isnon-isotropic by design.

11. As clause 2, where an optical film or sheet is integrated over theILED chips such that the light can be positioned or otherwise modifiedwithin the display.

12. As clause 2, where an optical film or sheet is integrated over theILED chips such that the light from ILED devices is selectivelymodified.

13. As clause 2, where the design of the mesa shape or contacts or sizeis varied in a predetermined manner to change beam profile.

14. As clause 1, where the display also includes electronic controlsystem.

15. As clause 14, where the electronic control is a passive matrix.

16. As clause 14, where the electronic control is an active matrix.

17. A display where the radiant distribution of light exiting from thedisplay may be dynamically varied by the user.

18. A display where the radiant distribution of light exiting from thedisplay may be varied automatically by the operating system.

19. As clause 18, where the operating system varies the viewing anglebased on information received from a sensor.

20. As clause 18, where the operating system varies the viewing anglebased on the number of people viewing the display.

21. As clause 18, where the operating system varies the viewing anglebased on the type of content on the display.

22. As clause 18, where the operating system varies the viewing anglebased on location of the display, for example, flat on a table.

23. As clause 18, where the operating system varies the viewing anglebased on orientation of the display, for example, portrait or landscape.

24. As clause 18, where the operating system varies the viewing anglebased on ambient lighting conditions.

The invention claimed is:
 1. A light emitting diode (LED) display,comprising: a plurality of inorganic (ILED) array chips, each ILED arraychip including a plurality of ILED emitters configured to emit lighthaving different emission beam angles and having a same color, each ILEDemitter of the plurality of ILED array chips providing a displaysub-pixel of the LED display, the plurality of ILED emitters of each ofthe plurality of ILED array chips providing display sub-pixels of adifferent color, each display pixel of the LED display including displaysub-pixels provided by multiple ILED emitters of different ILED arraychips; and a backplane attached with the plurality of ILED array chips,the backplane configured to provide drive currents to the plurality ofILED array chips, wherein, for each ILED array chip, the plurality ofILED emitters configured to emit light having different emission beamangles includes a first ILED emitter having an epitaxial layer of afirst mesa shape and a second ILED emitter having an epitaxial layer ofa second mesa shape, the first mesa shape and the second mesa shapebeing different.
 2. The LED display of claim 1, wherein the pluralityILED array chips include a first ILED array chip configured to emitlight having a red color, a second ILED array chip configured to emitlight having a blue color, and a third ILED array chip configured toemit light having a green color.
 3. The LED display of claim 1, whereinthe drive currents cause the plurality of ILED array chips to producedifferent viewing angles for different parts of the LED display.
 4. TheLED display of claim 1, wherein, for each ILED array chip, an emissionbeam angle of an ILED emitter is modified by one of a lens or a coating.5. The LED display of claim 1, wherein the plurality of ILED emitters ofeach of the plurality of ILED array chips are individually addressable.6. The LED display of claim 1, wherein, for each ILED array chip, thelight emitted by the plurality of ILED emitters is non-isotropic.
 7. Acomputer device, comprising: a light emitting diode (LED) display,comprising: a plurality of inorganic (ILED) array chips, each ILED arraychip including a plurality of ILED emitters configured to emit lighthaving different emission beam angles and having a same color, each ILEDemitter of the plurality of ILED array chips providing a displaysub-pixel of the LED display, the plurality of ILED emitters of each ofthe plurality of ILED array chips providing display sub-pixels of adifferent color, each display pixel of the LED display including displaysub-pixels provided by multiple ILED emitters of different ILED arraychips; and a backplane attached with the plurality of ILED array chips,the backplane configured to provide drive currents to the plurality ofILED array chips; and a processor configured to control the plurality ofILED array chips via the backplane to adjust a viewing angle of the LEDdisplay, wherein, for each ILED array chip, the plurality of ILEDemitters configured to emit light having different emission beam anglesincludes a first ILED emitter having an epitaxial layer of a first mesashape and a second ILED emitter having an epitaxial layer of a secondmesa shape, the first mesa shape and the second mesa shape beingdifferent.
 8. The computer device of claim 7, wherein the plurality ILEDarray chips include a first ILED array chip configured to emit lighthaving a red color, a second ILED array chip configured to emit lighthaving a blue color, and a third ILED array chip configured to emitlight having a green color.
 9. The computer device of claim 7, wherein,for each ILED array chip, an emission beam angle of an ILED emitter ismodified by one of a lens or a coating.
 10. The computer device of claim7, wherein the plurality of ILED emitters of each of the plurality ofILED array chips are individually addressable.